[PATCH 4.9 087/172] iwlwifi: fix kernel crash when unregistering thermal zone

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jens Axboe <axboe@xxxxxxxxx>


[ Upstream commit 92549cdc288f47f3a98cf80ac5890c91f5876a06 ]

A recent firmware change seems to have enabled thermal zones on the
iwlwifi driver. Unfortunately, my device fails when registering the
thermal zone. This doesn't stop the driver from attempting to unregister
the thermal zone at unload time, triggering a NULL pointer deference in
strlen() off the thermal_zone_device_unregister() path.

Don't unregister if name is NULL, for that case we failed registering.
Do the same for the cooling zone.

Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/wireless/intel/iwlwifi/mvm/tt.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/net/wireless/intel/iwlwifi/mvm/tt.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tt.c
@@ -843,8 +843,10 @@ static void iwl_mvm_thermal_zone_unregis
 		return;
 
 	IWL_DEBUG_TEMP(mvm, "Thermal zone device unregister\n");
-	thermal_zone_device_unregister(mvm->tz_device.tzone);
-	mvm->tz_device.tzone = NULL;
+	if (mvm->tz_device.tzone) {
+		thermal_zone_device_unregister(mvm->tz_device.tzone);
+		mvm->tz_device.tzone = NULL;
+	}
 }
 
 static void iwl_mvm_cooling_device_unregister(struct iwl_mvm *mvm)
@@ -853,8 +855,10 @@ static void iwl_mvm_cooling_device_unreg
 		return;
 
 	IWL_DEBUG_TEMP(mvm, "Cooling device unregister\n");
-	thermal_cooling_device_unregister(mvm->cooling_dev.cdev);
-	mvm->cooling_dev.cdev = NULL;
+	if (mvm->cooling_dev.cdev) {
+		thermal_cooling_device_unregister(mvm->cooling_dev.cdev);
+		mvm->cooling_dev.cdev = NULL;
+	}
 }
 #endif /* CONFIG_THERMAL */